Obesity and diabetes.

Obesity, particularly truncal obesity, is closely correlated to the prevalence of diabetes and cardiovascular disease. Plasma leptin, tumour necrosis factor-alpha and non-esterified fatty acid levels are all elevated in obesity and play a role in causing insulin resistance. Diabetic glycaemic control and insulin resistance improve with reductions in obesity, but the treatment of obesity is difficult, and sustained weight reduction rarely occurs with dietary management alone. Hypocaloric diets should be combined with education and low-impact exercise, as well as behavioural techniques used to encourage long-term changes. Weight-reducing drugs have a role in the management of obesity but only as part of such a total package. Newer anti-obesity drugs such as orlistat and sibutramine are well tolerated and have been shown to improve glycaemic control in diabetes. It is probable that drugs developed in the future will act at different sites in the pathways regulating body weight, but they may have to be used in combination.